Motorcycle Repair: Back firing after a short ride. wont start now., k n air filter, back fire

Question

sweet ride Hi Jan, I recently purchased a sweet 1974 cb450 cafe racer. I took it for a ride one night and it was glorious. Everything worked really well. The 2nd night i went to take it out for a spin and he reluctantly started after a few attempts accompanied by back fire through the K&N air filter on the left side. It did not back fire through the one on the right. it ran just a few feet and died. At this point the battery was losing juice so i just walked it back to the garage. What a disappointment that was. Hasn't started since. I'm not sure what it can be.. I bought a battery charger to see if it was just the battery and its charging as we speak. please help me!

Answer
It sounds like you have an ignition problem.  Your bike may have points so I would first check those (if it has them) to ensure the gap is correct and the opnening/closing time is correct.  First thing to do is make sure you are getting a good spark at the plugs.  Check the condenser also.  Make sure the bike is getting fuel, so open the drain screw on the carbs and make sure plenty of fuel is in the bowls.  Lastly check the integrity of the inlet carburrettor boots; it may be that  they are letting in false air.  Good luck,  Jan